One mole of octane (C8H18) fuels an internal combustion engine. When the octane burns in a cylinder the piston moves upward, as shown below. (Assume that air is an ideal gas and is 80%N2 and 20%O2.) Note that ALL of the O2 is used in the reaction. Answer the following questions using the data below. Assume that the heat capacities are constant over this temperature range. Be sure to use the correct sign for questions 4 and 5. What is the change in enthalpy (H) for the contents of the cylinder? (kJ) QUESTION 2 How many moles of oxygen are in the cylinder before reaction? QUESTION 3 What is the final gas temperature? (K) QUESTION 4 How much work is performed by the gas? (kJ) (Hint: The answer is a negative number.) QUESTION 5 What is the change in internal energy (U) for the gas in the cylinder? (kJ)